My truck didn't have those pieces with the original cab mounts and they did not come with the dogbones so I had no idea they were a part of the mount. Do I really need them? Could not having them cause the cab to be lower in the rear?

 

I will just not be as stiff side-to-side

 

Just for reference, as I was digging through my parts boxes looking for a few parts, I came upon two pairs of cab "dog bones". Both are different in design. Not sure if this would have an affect on the sagging of the cab.

 

The upper ones is what I had on the truck originally but the mounting holes were wallowed out and they were severely rusted. The lower ones are what I used to replace them. When I got them from LMC I was surprised that they were different but the distance between the mounting holes is the same...

 

The distance may be the same, but the overall shape is different and that might be allowing your cab to sag.

 

Just a thought:....The dogbones and related hardware need to be installed correctly because with nature of these frames and the considerable amount of flexing involved there needs to be clearance between the frame and cab underside. That is why these rear cab mounts are like they are, other wise a person could just bolt the cab directly to the frame only if you could stiffen the frame to stop the flexing. I noticed that under my 49 f1 the mounts were so badly worn that the cab bottom had worn indentifiable grooves in the frame. Hope this helps.
mervy49

 

I'm still not understanding how installing it wrong could cause the cab to sag. I can see where because of the design, the cab could sway more, but if the mounts did anything to the height, it would cause the cab to sit lower because of the green part in post 9.

Dave

 

It wouldn't cause the cab to sag regardless of which way the dogbone bolted in but I wonder if the bracket that fits toward the outside of the cab numbered 7C5388 in Ross's drawing could be mounted upside down to lift the cab higher?

 

You shouldn't have to do that, but I guess you could, providing the dogbone didn't hit the bracket. Have you tried loosening the bolts that hold that bracket on, to see if you can adjust it upwards a little? After years of being hammered downwards, it may be cutting into the bolts, too.

 

As I remember those bracket holes are not slotted so there's no adjustment. Right now the cab is sagging so badly that the back of the cab is in contact with the front bed panel near the top and the gap at the bottom of the cab is about three to four inches...can't hurt anything to turn the bracket upside down I suppose as long as the dogbone still fits....

 

If it is that bad, then there should be some obvious deformation of the cab floor, the brackets, etc. Could the front of the cab be too high for some reason? I know that would be strange, but...

Dave

 

If the two frame rails are somehow closer together it would also make the cab sit lower. Classic Haulers F-1 parts, has the adjustable dog bones and an adjustable frame mount that is adjustable up and down and side to side. It doesn't show a picture of it online but if you order a catalog it has a good picture in there. Adjustable frame mounts are $ 199.95 for the kit.

Classic Haulers F-1 Parts - Home

Classic Haulers F-1 Parts - Online Store

 

There's definitely nothing obvious and the front mounts are good...

 

That sounds like a LOT of difference. This is on your F-3? I wonder if the 'bones are different for big trucks, or if someone mounted the brackets in the wrong holes?

 

It is my understanding (scary concept) that the new cast style dog bones are the large truck ones and they have replaced the stamped tin ones.